One of the comments after last week's exploration of thick and thin communities asked the question what this distinction had to do with Isaiah Berlin. Indeed, Berlin was only mentioned once, at the end of the piece. It was a fair point. But what I was hoping to do was to map a particular way of seeing the difference between liberalism (which prizes the values of thin communities) and what we might roughly call communitarianism (which prizes the values of thick communities). My intention in setting up this particular distinction was to lay it alongside Berlin's own distinction between negative and positive liberty – creating a link between liberalism, negative liberty and thin communities, and communitarianism, positive liberty and thick communities. Like all intellectual maps, this one works only so far, but I think it may enable us to notice various connections.

One of the problems with negative liberty – the idea that freedom consists simply of the absence of external constrains – is that it seems to assume that all types of freedom are more or less equally important. Take, for instance, the example that Charles Taylor gives in his excellent essay What's Wrong With Negative Liberty. He asks us to consider a "diabolical defence of Albania as a free country". The argument goes like this: Tirana is freer than London because, although religion has been abolished in Albania, Tirana has fewer traffic lights.

"After all, only a minority of Londoners practise some religion in public places, but all have to negotiate their way through traffic. In sheer quantitative terms, the number of acts restricted by traffic lights must be greater than restricted by a ban on public religious practice. So if Britain is considered a free country, why not Albania?"

The point Taylor is making is that some types of freedom are seen as more important than others because we all work according to some horizon of significance against which various different types can be evaluated. Some kinds of freedom are in fact more important than others. Negative freedom – freedom simply as the absence of external constraint – has no way of articulating this.

As Taylor goes on to argue, freedom is important because we are "purposive beings". Freedom makes sense only against the background of a sense of what human life is for, some sense of teleology. Only when this background is recognised can we articulate why it is that we care less about traffic lights infringing our freedom than we do about a ban on religious worship.

The concept of positive freedom, on the other hand, argues that some form of constraint or obligation is required for higher forms of freedom to flourish. And thus we are forced to decide between greater and lesser expressions of freedom on the basis of some agreed sense of what human life is for. Positive freedom needs to carry, at least in some minimal sense, a big story – what, since Lyotard, we have disparagingly learned to call a meta-narrative.

And my contention here is that thick communities are much better at generating a sense of identity around some big story. For centuries, and for good or ill, Christianity was that story for the west. But as secularisation diminishes the influence of that story, the question is what replaces it. My problem with liberalism is that, when it is understood simply as the exercise of negative liberty, it is not able to generate that story on its own. The story of freedom, as told by liberalism, isn't really a story at all – which is why liberalism is good at saying what it is against (external constraint) but not terribly good at saying what it is for – other than some vague and content-less expression of freedom. That's fine for slogans, but not much more.